Reading Levels (RL) Reading levels are based on the actual difficulty of the words, grammar, sentence structure, etc., used in a book. The first number is the year in school and the second number is the month. A reading level of 5.2 means that a student in the second month of fifth grade should be able to read the book without much difficulty. Reading Levels range from 1.0 through 8.9. Any grade above 8.9 is considered Young Adult.